Ever try Acetal (Delrin) for dark slides?

Discussion in 'Camera Building, Repairs & Modification' started by Steve Goldstein, Jul 13, 2008.

  1. Steve Goldstein

    Steve Goldstein Subscriber

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    I found thin black Delrin sheets available from McMaster-Carr and onlinemetals.com. Has anyone ever tried using this for dark slides? It's lighter than aluminum, on the order of Garolite XX, and has nice low-friction properties. I may just order a 1/32" sheet to play around with, but it would be nice to know ahead of time if there are any issues with this material.

    BTW, I purchased a thin (0.023") sheet of carbon-fiber material recently. It won't do for a dark slide, at least this thin - it's not entirely opaque! Open areas in the weave lead to optical pinholes. A thicker sheet might not suffer from this, but aluminum, garolite, and (I hope) Delrin don't have this problem and are less costly as well.
     
  2. keithwms

    keithwms Member

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    Haven't tried it for dark slides but I think it should be fine, I've made various odds and ends with it. It doesn't seem to shed, is fairly fracture resistant when machined, and has good thermal properties. It reminds me of the stuff the fidelity holders are made of.

    I am currently drawing up plans for a film holder/adapter which will be made in delrin.
     
  3. eclarke

    eclarke Member

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    The delrin is probably not opaque either. At 1/32" it will also become soft and floppy if it gets a little warm. Look for black vulcanized fibre....EC
     
  4. Greg_E

    Greg_E Member

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    The white delrin I have in 1/4 inch is absolutely not opaque! Not sure about the black stuff, but probably not going to be opaque enough for a dark slide. My suggestion would be to cover it with an aluminum tape if you can get the tape large enough, or maybe have it plated with a metal.

    If you need thin and completely light proof, you might see about copper clad circuit board material. Single sided might be cheap enough to do what you need.
     
  5. Mick Fagan

    Mick Fagan Subscriber

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    I use 1.6mm white Delrin on a LASER machine, have done for over 12 years.

    Not sure about the opacity, or lack thereof, but it is a dimensionally stable product in that when it is cut through with the LASER, or engraved to a depth of .65mm. Both of these things cause enough heat to vaporise the unwanted material and allow me to cut accurately to 1/600 of an inch (American LASER) in a three dimensional manner for making both male and female embossing dies.

    I don't think it would take too kindly to bending, probably snap quite quickly.

    Mick.
     
  6. Thomas Bertilsson

    Thomas Bertilsson Subscriber

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    Acetal is a material often used in bearings, mainly for its dimensional stability as well as low friction. I've seen them in air duct dampers, for instance, and those dampers were rated to 180*F, so they must be able to take heat quite successfully. But since the bearings are encased, I don't know if they would indeed become soft at that temperature or not.
    - Thomas
     
  7. barryjyoung

    barryjyoung Member

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    Black acetal is not opaque enough and will not be rigid enough in 1/32 thickness unless you are making very small darkslides. I would recommend black phenolic which is available in sheets nearly as smooth as acetal. It is truly opaque for visible light and so far my experiments also indicate that it is opaque to IR. Garolite works fine for larger darkslides though I prefer the smooth phenolic sheets. Phenolic also does not dent or bend like aluminum. It is the best material I have found.
     
  8. CRhymer

    CRhymer Subscriber

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    Hello Barry,
    Can you tell us a good source for black phenolic?
    Thank you.
    Cheers,
    Clarence
     
  9. barryjyoung

    barryjyoung Member

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    Hi Clarence:

    You could try:

    Ridout Plastics Company Inc.
    5535 Ruffin Rd.
    San Diego, California 92123

    phone 858.560.1551
    fax 858.560.1941

    http://www.ridoutplastics.com/

    They have the smooth phenolic. I had a customer service problem with them and have stopped using them, but may have to go back to them since I have had even worse service from three other plastics houses.

    Mike Jimenez is a great guy to work with but some of the others there aren't. You can reach Mike at mike@ridoutplastics.com

    If you do talk to Ridout, please tell them I sent you. I have no affiliation with them, but it might make it easier when I crawl back there on my hands and knees begging for smooth paper based XX grade black phenlic sheet.

    I have not found it anywhere else, and this is the right stuff. Garolite has a rough finish like it has been ground, this stuff is smooth and shiny like acetal.

    Good luck
     
  10. Greg_E

    Greg_E Member

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